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| author | Simon Marlow <marlowsd@gmail.com> | 2018-07-12 10:13:47 -0400 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2018-07-12 15:04:20 -0400 |
| commit | 7fc418df856d9b58034eeec48915646e67a7a562 (patch) | |
| tree | 656a7a8ae131122c4253bb6c490fb9e7db671346 /rts/SMPClosureOps.h | |
| parent | 1a79270c72cfcd98d683cfe7b2c777d8dd353b78 (diff) | |
| download | haskell-7fc418df856d9b58034eeec48915646e67a7a562.tar.gz | |
Fix deadlock between STM and throwTo
There was a lock-order reversal between lockTSO() and the TVar lock,
see #15136 for the details.
It turns out we can fix this pretty easily by just deleting all the
locking code(!). The principle for unblocking a `BlockedOnSTM` thread
then becomes the same as for other kinds of blocking: if the TSO
belongs to this capability then we do it directly, otherwise we send a
message to the capability that owns the TSO. That is, a thread blocked
on STM is owned by its capability, as it should be.
The possible downside of this is that we might send multiple messages
to wake up a thread when the thread is on another capability. This is
safe, it's just not very efficient. I'll try to do some experiments
to see if this is a problem.
Test Plan: Test case from #15136 doesn't deadlock any more.
Reviewers: bgamari, osa1, erikd
Reviewed By: osa1
Subscribers: rwbarton, thomie, carter
GHC Trac Issues: #15136
Differential Revision: https://phabricator.haskell.org/D4956
Diffstat (limited to 'rts/SMPClosureOps.h')
| -rw-r--r-- | rts/SMPClosureOps.h | 9 |
1 files changed, 0 insertions, 9 deletions
diff --git a/rts/SMPClosureOps.h b/rts/SMPClosureOps.h index 1d18e1b018..c73821a782 100644 --- a/rts/SMPClosureOps.h +++ b/rts/SMPClosureOps.h @@ -124,15 +124,6 @@ EXTERN_INLINE void unlockClosure(StgClosure *p, const StgInfoTable *info) p->header.info = info; } -// Handy specialised versions of lockClosure()/unlockClosure() -INLINE_HEADER void lockTSO(StgTSO *tso); -INLINE_HEADER void lockTSO(StgTSO *tso) -{ lockClosure((StgClosure *)tso); } - -INLINE_HEADER void unlockTSO(StgTSO *tso); -INLINE_HEADER void unlockTSO(StgTSO *tso) -{ unlockClosure((StgClosure*)tso, (const StgInfoTable *)&stg_TSO_info); } - #endif /* CMINUSMINUS */ #include "EndPrivate.h" |